It is common practice in the materials handling and distribution industries to employ load-bearing platforms, called "pallets", for movement of articles. These pallets are most often manufactured from materials including wood, plastic, metal or paper, and are stacked with articles such as packed corrugated cardboard or fiberboard boxes. Most pallets provide the capability to lift and move a stack of boxes or cartons with a pallet truck or forklift, which permits the movement of multiple articles at the same time without handling each article individually. This increases the efficiency of the article transport and reduces the likelihood of damage to the individual articles, all for the purpose of doing so at lower cost.
Designs of pallets are intended to achieve a number of objectives and sometimes those individual requirements create design conflicts and engineering trade-offs. One such trade-off is that each pallet is typically designed for a specific article or commodity group for delivery in a specific market. As such, it is required to meet the dimensional standards of the particular market sector it is being employed by. Since different market sectors have different dimensional requirements, pallet dimensions designed for one market sector often are incompatible with the requirements of other markets. For shippers sending articles to multiple markets, this increases the number of pallet types and associated expenses necessary to maintain multiple inventories. For example, cartons used for shipping a particular manufactured item may be of different dimensions than cartons designed for shipment of fresh produce, so pallets which adequately support cartons of fresh produce will not necessarily adequately support particular manufactured items.
Some pallets are designed for a onetime, temporary use and are typically constructed of lightweight and inexpensive components such as lesser quality wood beams and boards. Other pallets are designed for multiple uses and employ various materials, most commonly lumber, plastic and/or metals, to ensure structural robustness throughout the life of the pallet. Consequently, the reusable pallets typically weigh and cost more than one-time use pallets.
Because pallets usually travel in distribution together with the articles being conveyed, and because heavier objects normally cost more to handle and to transport than lighter objects, heavier pallets may considerably increase handling and distribution costs for a particular commodity. Heavier pallets may also increase the risk of injury to the cargo handler, further decreasing their utility. But, lighter weight pallets may lack sufficient structural robustness to survive even a single, arduous handling.
Another design trade-off is the need to provide a solid, stable platform easily handled by forklifts and other equipment, and yet being capable of efficient return shipment for reuse. For example, conveyed articles are very often in corrugated paper containers, also known as "cardboard boxes". These cardboard boxes perform best when fully supported by the conveying pallet, particularly when moisture is present as is common with refrigerated distribution channels. This need for full support is particularly true of the edges and corners of the boxes, which provide most of the stacking strength of the box. For efficient distribution, boxes are stacked vertically on pallets to fully cover the pallet top deck width and length. To achieve effective support to a stack of several cardboard boxes, the optimal pallet design provides a pallet deck face which is completely or almost completely solid.
In general, pallets are required to have space underneath the deck adequate for pallet handling equipment to engage, lift and transport the loaded pallet. Most pallets include some form of blocks or legs sufficient to elevate the pallet deck.
Reusable pallets usually must be returned to their point of origin for reuse. For example, shipments of a particular type of produce may be received via sea-going ship at a port city where pallets of boxed produce are unloaded from the ship hold into overland trucks. The trucks then transport the loaded pallets to inland distribution centers, and the empty pallets must be returned to the port city for reuse. As such, it is desirable that the volume of cargo space required to return the empty, unloaded pallets be significantly less than that used when conveying articles. Typical industry designs for such pallets employ a hole in the deck directly above a hollow block or leg so that when stacked vertically the pallet legs can nest like conical paper cups. The larger the leg, the more stable the loaded pallet is during handling, but holes and spaces in the deck may interfere with proper support of the boxes, particularly since the legs of the pallet are typically located at the corners and periphery of the pallet which physically coincides with the corners of the corrugated boxes nearest to the corners and periphery. Consequently, the corrugated boxes directly above these leg holes often sag or break due to the absence of support, causing packaging failure and article damage. In severe instances the boxes may not stay contained on the pallet causing a safety hazard as well as severe article damage.
Therefor, there is a need in the art for a shipping pallet which can easily accommodate the varying dimensional requirements of different products and markets without expensive or complex modification in order to avoid the expense of multiple inventories of pallets. Further, to maximize support of the conveyed articles, there is a need in the art for this pallet to have a completely or nearly solid upper deck. Preferably, this new pallet must be robust and as light in weight as possible to optimize cargo handler safety and minimize shipment costs. And, there is a need in the art for this new pallet to permit nesting in a simple fashion and for efficient return for reuse. This pallet must achieve these objectives and also perform the basic functions of a typical pallet of proper load handling without compromise or complexity.